03-02-2008
Quote:
Originally Posted by
fpmurphy
When a user logs in using login(1) login sets the $HOME environmental variable. The shell uses that environmental variable to find a users home directory.
AFAIK, there is no single API which will check whether a login is known to all authentication methods (local, NIS, PAM, etc.) used on a particular system.
Thanks for your answer.
That is true for the current user, who is obviously logged in. However, if I have an existing user, say bob with HOME=/home/bob, on a system, then anyone will see ~bob expanded to /home/bob in their shell. Without that bob has ever logged in (and so called login(1)), and regardless of the authentication method as far as I could experiment...
On the other hand, if bob doesn't exist, then ~bob won't expand.
So the shell knows whether a user exists or not... the question is how?
which I should find in the sources
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LEARN ABOUT CENTOS
drop_user_mapping
DROP USER
MAPPING(7) PostgreSQL 9.2.7 Documentation DROP USER MAPPING(7)
NAME
DROP_USER_MAPPING - remove a user mapping for a foreign server
SYNOPSIS
DROP USER MAPPING [ IF EXISTS ] FOR { user_name | USER | CURRENT_USER | PUBLIC } SERVER server_name
DESCRIPTION
DROP USER MAPPING removes an existing user mapping from foreign server.
The owner of a foreign server can drop user mappings for that server for any user. Also, a user can drop a user mapping for his own user
name if USAGE privilege on the server has been granted to the user.
PARAMETERS
IF EXISTS
Do not throw an error if the user mapping does not exist. A notice is issued in this case.
user_name
User name of the mapping. CURRENT_USER and USER match the name of the current user. PUBLIC is used to match all present and future
user names in the system.
server_name
Server name of the user mapping.
EXAMPLES
Drop a user mapping bob, server foo if it exists:
DROP USER MAPPING IF EXISTS FOR bob SERVER foo;
COMPATIBILITY
DROP USER MAPPING conforms to ISO/IEC 9075-9 (SQL/MED). The IF EXISTS clause is a PostgreSQL extension.
SEE ALSO
CREATE USER MAPPING (CREATE_USER_MAPPING(7)), ALTER USER MAPPING (ALTER_USER_MAPPING(7))
PostgreSQL 9.2.7 2014-02-17 DROP USER MAPPING(7)